Posterolateral Premature Ventricular Complex Manifest as Posteroseptal Premature Ventricular Complex: A Case Report

Premature ventricular complex (PVC) is one of the most common arrhythmias detected in young patients. We report a case of a young patient with symptomatic high-burden PVC suspected to originate from the posterior right ventricular outflow tract (RVOT) who underwent an electrophysiology study (EPS) and was subsequently successfully ablated with markedly reduced PVC burden. The following day, it was noted that there was a change in PVC morphology. A repeat 3D electroanatomical mapping localized the second PVC morphology to posterolateral RVOT and abolished it with radiofrequency ablation (RFA).


Introduction
Premature ventricular complex (PVC) is one of the most common arrhythmias detected in young patients.We report a case of a young patient with symptomatic high-burden PVC suspected to originate from the posteroseptal right ventricular outflow tract (RVOT), who underwent an electrophysiology study (EPS) and shifted to posterolateral PVC RVOT on the following day.The posterolateral PVC RVOT successfully ablated and returned to normal sinus rhythm with difficulty maneuvering the ablation catheter.

Case Presentation
A 36-year-old lady with underlying hypertension and dyslipidemia complained of non-progressive intermittent central chest pain radiating to the left upper back for three years.The pain was described as dull, aching, and continuous in nature.She was able to cycle for more than three hours without limitation.She had no symptoms of syncope, acute coronary syndrome, or heart failure in the past.The clinical examination was unremarkable.The ECG is shown in Figure 1.Twenty-four-hour Holter monitoring showed a unifocal PVC burden of 30%.Echocardiography showed a structurally normal heart.CT coronary angiography showed normal origin and patent coronary arteries.Hence, she was diagnosed with symptomatic unifocal PVC.Based on surface ECG, the PVC had an LBBB morphology with an inferior axis; transitions occurred at V3, rS in lead V1, and an R pattern in V6 suggestive of origin from the posteroseptal RVOT.After the failure of beta-blocker therapy for one year for symptomatic relief, she agreed to undergo EPS and radiofrequency ablation (RFA).
The procedure was done using CARTO 3D mapping with a THERMOCOOL SMARTTOUCH® catheter from Biosense Webster (Irvine, CA).Mapping was done during PVC for the earliest ventricular electrogram (EGM).
The earliest activation breakthrough site of PVC was localized to posteriorseptal RVOT and measured 30 ms earlier than the PVC template (Video 1).
View video here: https://youtu.be/v4CazxDY3qg A pace map was performed, and the PVC match was 93.6%; however, attempted ablation was unsuccessful.RVOT was remapped, and the earlier breakthrough site shifted inferiorly; thus, further lesions were delivered along the same line from the superior to the inferior site within the vicinity of a centimeter.Post-ablation, monitoring the patient for 30 minutes revealed that the PVC frequency was reduced, the procedure was stopped, and the patient was put under observation.
The next day, a patient had persistent symptoms and documented unifocal PVC of slightly different morphology than the first one, as shown in Figure 2. The patient consented to repeat the procedure.The coronary cusps were mapped during PVC using the femoral artery approach, but the earliest breakthrough site was 28 ms before surface ECG.The attempted ablation failed to suppress the PVC.Thus, RVOT was remapped.We identified a pre-systolic sharp potential preceding the QRS onset during PVC by 47 ms at the posterolateral aspect of RVOT with 95.9% similarity to the PVC template (Video 2).
VIDEO 2: Propagation map showed the PVC site of origin shift to posterolateral RVOT.
View video here: https://youtu.be/ViIVCkIIz7Y This spot is opposite the earliest area identified over the left coronary cusp, as shown in Figure 3.The PVCs were immediately suppressed with ablation at 30 W in irrigated mode.The lesion was consolidated, and the patient was observed for 30 minutes and showed no recurrence of PVC.There were no complications throughout the procedure.The patient was discharged with a repeated ECG showing sinus rhythm the next day.At the six-month follow-up, the patient was asymptomatic with no documented PVC on the ECG or Holter.

FIGURE 1 :
FIGURE 1: ECG showed PVC with LBBB morphology, the inferior axis with the transition at V3, which suggests the site of the location at posteroseptal RVOT.PVC: premature ventricular complex, LBBB: left bundle branch block, RVOT: right ventricular outflow tract.

FIGURE 2 :
FIGURE 2: ECG post-first procedure show changed of PVC morphology and transition point.